Mitigation mechanism of ultrafiltration membrane fouling by Fe2+ with hydrogen peroxide for protein-rich wastewater treatment

Membrane fouling caused by protein-like organic matter is a major challenge during ultrafiltration in food wastewater treatment. In this work, 0.3 mM hydrogen peroxide (H2O2) and 0.15 mM Fe2+ were added to three typical protein-rich wastewaters, and macro- and microanalyses were performed to unravel their influence on membrane protein fouling. The results showed that for bovine serum protein, lysozyme or soya protein, pre-treatment with H2O2&Fe2+ reduced the membrane flux decline rate by more than 50 % and improved the flux recovery rate by 60 %. This is because the small quantity of Fe2+&H2O2 could induce the Fenton reaction without pH pre-adjustment, which was accompanied by oxidation and coagulation. Then, the synergistic effect of oxidation and coagulation promoted protein molecules to clump together to form large aggregates, while the adhesion forces of proteins at the membrane surface were weakened by oxidation. These factors eventually mitigated the protein deposition rate onto the membrane surface and resulted in a more porous and loose fouling layer. Moreover, the added iron ions effectively bound with protein molecules and were intercepted by the ultrafiltration membrane, which avoided secondary pollution.